kernel/linux.git/fs/zonefs/zonefs.h, branch v7.1

zonefs: fix synchronous direct writes to sequential files

2023-08-10T03:59:47+00:00

Commit 16d7fd3cfa72 ("zonefs: use iomap for synchronous direct writes") changes zonefs code from a self-built zone append BIO to using iomap for synchronous direct writes. This change relies on iomap submit BIO callback to change the write BIO built by iomap to a zone append BIO. However, this change overlooked the fact that a write BIO may be very large as it is split when issued. The change from a regular write to a zone append operation for the built BIO can result in a block layer warning as zone append BIO are not allowed to be split. WARNING: CPU: 18 PID: 202210 at block/bio.c:1644 bio_split+0x288/0x350 Call Trace: ? __warn+0xc9/0x2b0 ? bio_split+0x288/0x350 ? report_bug+0x2e6/0x390 ? handle_bug+0x41/0x80 ? exc_invalid_op+0x13/0x40 ? asm_exc_invalid_op+0x16/0x20 ? bio_split+0x288/0x350 bio_split_rw+0x4bc/0x810 ? __pfx_bio_split_rw+0x10/0x10 ? lockdep_unlock+0xf2/0x250 __bio_split_to_limits+0x1d8/0x900 blk_mq_submit_bio+0x1cf/0x18a0 ? __pfx_iov_iter_extract_pages+0x10/0x10 ? __pfx_blk_mq_submit_bio+0x10/0x10 ? find_held_lock+0x2d/0x110 ? lock_release+0x362/0x620 ? mark_held_locks+0x9e/0xe0 __submit_bio+0x1ea/0x290 ? __pfx___submit_bio+0x10/0x10 ? seqcount_lockdep_reader_access.constprop.0+0x82/0x90 submit_bio_noacct_nocheck+0x675/0xa20 ? __pfx_bio_iov_iter_get_pages+0x10/0x10 ? __pfx_submit_bio_noacct_nocheck+0x10/0x10 iomap_dio_bio_iter+0x624/0x1280 __iomap_dio_rw+0xa22/0x18a0 ? lock_is_held_type+0xe3/0x140 ? __pfx___iomap_dio_rw+0x10/0x10 ? lock_release+0x362/0x620 ? zonefs_file_write_iter+0x74c/0xc80 [zonefs] ? down_write+0x13d/0x1e0 iomap_dio_rw+0xe/0x40 zonefs_file_write_iter+0x5ea/0xc80 [zonefs] do_iter_readv_writev+0x18b/0x2c0 ? __pfx_do_iter_readv_writev+0x10/0x10 ? inode_security+0x54/0xf0 do_iter_write+0x13b/0x7c0 ? lock_is_held_type+0xe3/0x140 vfs_writev+0x185/0x550 ? __pfx_vfs_writev+0x10/0x10 ? __handle_mm_fault+0x9bd/0x1c90 ? find_held_lock+0x2d/0x110 ? lock_release+0x362/0x620 ? find_held_lock+0x2d/0x110 ? lock_release+0x362/0x620 ? __up_read+0x1ea/0x720 ? do_pwritev+0x136/0x1f0 do_pwritev+0x136/0x1f0 ? __pfx_do_pwritev+0x10/0x10 ? syscall_enter_from_user_mode+0x22/0x90 ? lockdep_hardirqs_on+0x7d/0x100 do_syscall_64+0x58/0x80 This error depends on the hardware used, specifically on the max zone append bytes and max_[hw_]sectors limits. Tests using AMD Epyc machines that have low limits did not reveal this issue while runs on Intel Xeon machines with larger limits trigger it. Manually splitting the zone append BIO using bio_split_rw() can solve this issue but also requires issuing the fragment BIOs synchronously with submit_bio_wait(), to avoid potential reordering of the zone append BIO fragments, which would lead to data corruption. That is, this solution is not better than using regular write BIOs which are subject to serialization using zone write locking at the IO scheduler level. Given this, fix the issue by removing zone append support and using regular write BIOs for synchronous direct writes. This allows preseving the use of iomap and having identical synchronous and asynchronous sequential file write path. Zone append support will be reintroduced later through io_uring commands to ensure that the needed special handling is done correctly. Reported-by: Shin'ichiro Kawasaki Fixes: 16d7fd3cfa72 ("zonefs: use iomap for synchronous direct writes") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal Tested-by: Shin'ichiro Kawasaki Reviewed-by: Christoph Hellwig

zonefs: use iomap for synchronous direct writes

2023-06-13T23:51:05+00:00

Remove the function zonefs_file_dio_append() that is used to manually issue REQ_OP_ZONE_APPEND BIOs for processing synchronous direct writes and use iomap instead. To preserve the use of zone append operations for synchronous writes, different struct iomap_dio_ops are defined. For synchronous direct writes using zone append, zonefs_zone_append_dio_ops is introduced. The submit_bio operation of this structure is defined as the function zonefs_file_zone_append_dio_submit_io() which is used to change the BIO opreation for synchronous direct IO writes to REQ_OP_ZONE_APPEND. In order to preserve the write location check on completion of zone append BIOs, the end_io operation is also defined using the function zonefs_file_zone_append_dio_bio_end_io(). This check now relies on the zonefs_zone_append_bio structure, allocated together with zone append BIOs with a dedicated BIO set. This structure include the target inode of a zone append BIO as well as the target append offset location for the zone append operation. This is used to perform a check against bio->bi_iter.bi_sector when the BIO completes, without needing to use the zone information z_wpoffset field, thus removing the need for taking the inode truncate mutex. Signed-off-by: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Johannes Thumshirn Reviewed-by: Himanshu Madhani

zonefs: Cache zone group directory inodes

2023-01-23T00:25:51+00:00

Since looking up any zone file inode requires looking up first the inode for the directory representing the zone group of the file, ensuring that the zone group inodes are always cached is desired. To do so, take an extra reference on the zone groups directory inodes on mount, thus avoiding the eviction of these inodes from the inode cache until the volume is unmounted. Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn

zonefs: Dynamically create file inodes when needed

2023-01-23T00:25:51+00:00

Allocating and initializing all inodes and dentries for all files results in a very large memory usage with high capacity zoned block devices. For instance, with a 26 TB SMR HDD with over 96000 zones, mounting the disk with zonefs results in about 130 MB of memory used, the vast majority of this space being used for vfs inodes and dentries. However, since a user will rarely access all zones at the same time, dynamically creating file inodes and dentries on demand, similarly to regular file systems, can significantly reduce memory usage. This patch modifies mount processing to not create the inodes and dentries for zone files. Instead, the directory inode operation zonefs_lookup() and directory file operation zonefs_readdir() are introduced to allocate and initialize inodes on-demand using the helper functions zonefs_get_dir_inode() and zonefs_get_zgroup_inode(). Implementation of these functions is simple, relying on the static nature of zonefs directories and files. Directory inodes are linked to the volume zone groups (struct zonefs_zone_group) they represent by using the directory inode i_private field. This simplifies the implementation of the lookup and readdir operations. Unreferenced zone file inodes can be evicted from the inode cache at any time. In such case, the only inode information that cannot be recreated from the zone information that is saved in the zone group data structures attached to the volume super block is the inode uid, gid and access rights. These values may have been changed by the user. To keep these attributes for the life time of the mount, as before, the inode mode, uid and gid are saved in the inode zone information and the saved values are used to initialize regular file inodes when an inode lookup happens. The zone information mode, uid and gid are initialized in zonefs_init_zgroup() using the default values. With these changes, the static minimal memory usage of a zonefs volume is mostly reduced to the array of zone information for each zone group. For the 26 TB SMR hard-disk mentioned above, the memory usage after mount becomes about 5.4 MB, a reduction by a factor of 24 from the initial 130 MB memory use. Co-developed-by: Jorgen Hansen Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn

zonefs: Separate zone information from inode information

2023-01-23T00:25:51+00:00

In preparation for adding dynamic inode allocation, separate an inode zone information from the zonefs inode structure. The new data structure zonefs_zone is introduced to store in memory information about a zone that must be kept throughout the lifetime of the device mount. Linking between a zone file inode and its zone information is done by setting the inode i_private field to point to a struct zonefs_zone. Using the i_private pointer avoids the need for adding a pointer in struct zonefs_inode_info. Beside the vfs inode, this structure is reduced to a mutex and a write open counter. One struct zonefs_zone is created per file inode on mount. These structures are organized in an array using the new struct zonefs_zone_group data structure to represent zone groups. The zonefs_zone arrays are indexed per file number (the index of a struct zonefs_zone in its array directly gives the file number/name for that zone file inode). Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn

zonefs: Reduce struct zonefs_inode_info size

2023-01-23T00:25:51+00:00

Instead of using the i_ztype field in struct zonefs_inode_info to indicate the zone type of an inode, introduce the new inode flag ZONEFS_ZONE_CNV to be set in the i_flags field of struct zonefs_inode_info to identify conventional zones. If this flag is not set, the zone of an inode is considered to be a sequential zone. The helpers zonefs_zone_is_cnv(), zonefs_zone_is_seq(), zonefs_inode_is_cnv() and zonefs_inode_is_seq() are introduced to simplify testing the zone type of a struct zonefs_inode_info and of a struct inode. Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn

zonefs: Simplify IO error handling

2023-01-23T00:25:51+00:00

Simplify zonefs_check_zone_condition() by moving the code that changes an inode access rights to the new function zonefs_inode_update_mode(). Furthermore, since on mount an inode wpoffset is always zero when zonefs_check_zone_condition() is called during an inode initialization, the "mount" boolean argument is not necessary for the readonly zone case. This argument is thus removed. zonefs_io_error_cb() is also modified to use the inode offline and zone state flags instead of checking the device zone condition. The multiple calls to zonefs_check_zone_condition() are reduced to the first call on entry, which allows removing the "warn" argument. zonefs_inode_update_mode() is also used to update an inode access rights as zonefs_io_error_cb() modifies the inode flags depending on the volume error handling mode (defined with a mount option). Since an inode mode change differs for read-only zones between mount time and IO error time, the flag ZONEFS_ZONE_INIT_MODE is used to differentiate both cases. Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn

zonefs: Reorganize code

2023-01-23T00:25:50+00:00

Move all code related to zone file operations from super.c to the new file.c file. Inode and zone management code remains in super.c. Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn

zonefs: Fix active zone accounting

2022-11-25T08:01:22+00:00

If a file zone transitions to the offline or readonly state from an active state, we must clear the zone active flag and decrement the active seq file counter. Do so in zonefs_account_active() using the new zonefs inode flags ZONEFS_ZONE_OFFLINE and ZONEFS_ZONE_READONLY. These flags are set if necessary in zonefs_check_zone_condition() based on the result of report zones operation after an IO error. Fixes: 87c9ce3ffec9 ("zonefs: Add active seq file accounting") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn

zonefs: Add active seq file accounting

2022-04-20T23:37:56+00:00

Modify struct zonefs_sb_info to add the s_active_seq_files atomic to count the number of seq files representing a zone that is partially written or explicitly open, that is, to count sequential files with a zone that is in an active state on the device. The helper function zonefs_account_active() is introduced to update this counter whenever a file is written or truncated. This helper is also used in the zonefs_seq_file_write_open() and zonefs_seq_file_write_close() functions when the explicit_open mount option is used. The s_active_seq_files counter is exported through sysfs using the read-only attribute nr_active_seq_files. The device maximum number of active zones is also exported through sysfs with the read-only attribute max_active_seq_files. Signed-off-by: Damien Le Moal Reviewed-by: Johannes Thumshirn Reviewed-by: Hans Holmberg